In recent years, white LED devices have been widely used in which phosphors, such as YAG phosphor, are disposed near gallium nitride (GaN)-based blue light emitting diode (LED) chips. Such white LED devices provide white light by mixing blue light emitted from blue LED chips and yellow light emitted from phosphors that have received blue light. Other white LED devices have been also developed in which phosphors that emit green or red fluorescence are disposed near blue LED chips. Such white LED devices provide white light by mixing blue light emitted from blue LED chips and red and green light emitted from phosphors that have received blue light.
There are various applications of white LED devices, and these white LED devices have recently replaced fluorescent lamps and incandescent lamps. Such lighting devices contain a number of white LED devices. Therefore, it is important to increase the light extraction efficiency of each white LED device in order to achieve cost reduction and life extension of the lighting devices. It is also important to increase the light extraction efficiency not only of white LED devices but also of single-color LED devices with no phosphor.
Conventional LED devices have suffered from difficulty in increasing the light extraction efficiency because substrates having LED elements tend to absorb the light from the LED elements and the fluorescence from phosphors. LED devices have been thus developed in which reflectors with high light reflectance are disposed around LED elements. Such reflectors are generally formed from plated metal or the like.
However, reflectors formed from plated metal are conductive. Therefore, such reflectors cannot be formed all over the substrate, which has imposed a problem that the substrate in the area having no reflector formed thereon absorbs light. On the other hand, a reflector formed by covering plated metal with a resin layer (Patent Literature 1) and a reflector formed by covering plated metal with a white resin layer (Patent Literature 2) have been also proposed.